The law enforcement representative with the close-cropped blond hair and jutting jaw paced the platforms of New Jersey’s busiest train station, searching for signs of suspicious behavior.

He checked for explosive materials in the slots of ticket vending machines and under the seats of a train at Newark Penn Station. He inspected garbage cans and a stray duffel bag.

When his shift was over, he retreated to the break room and wagged his tail.

"We’re out there and we’re visible, so it makes people feel good," said NJ Transit Police Sgt. Cindy Garcia, who handles the police dog Sampson. "It makes people feel like they have confidence in the fact that the station is safe, the trains are safe. They can get to work, their kids are going to school and they’re not worrying."

In Sampson and Garcia, NJ Transit Police has two law enforcement representatives who stand out for their uniqueness.

Sampson, 1 1/2 years old, is the only yellow lab on a team of dogs sniffing for explosives and guns at NJ Transit stations. The others are German shepherds.

And Garcia, 36, is the first woman to head the department’s prestigious K-9 division.

In her 10th year with the NJ Transit Police — America’s only transit policing agency with statewide authority and jurisdiction — Garcia leads a team of 14 officers and 15 dogs trained and assigned to patrol the agency’s trains, buses, light rail vehicles and stations.

The K-9 unit became more vital after the Sept. 11, 2001, terror attacks served notice the heavily populated New York metropolitan area was a preferred target.

NJ Transit Police Chief Christopher Trucillo said all but one of the dogs are trained to detect explosives.

"That’s what we’re concerned about, based on everything we’ve seen around the globe," he said. "The K-9 unit, in our terror/counterterrorism initiatives, is probably the most critical component."

The K-9 division, which also includes a narcotics-sniffing dog, covers the whole state.

"Cindy’s leadership and her enthusiasm for that position is really going to enhance it," Trucillo said. "She works well with the officers involved. She’s got a great relationship with her new K-9 partner, Sampson, and we’re real proud of her."

Policewoman and pooch have been a team for six months, when they began bonding during 13 weeks of training sessions in Atlantic County.

Dogs are "imprinted" with 24 different types of odors for explosives, starting with basic black powder and progressing to more difficult scents.

In a process called "cooking," white towels are rolled like newspapers and placed in a sealed bag next to a jar of explosives. Over three to five days, the towels absorb the odor of the explosive. Then the towels are used in a game of fetch with the dog, which uses its saliva and powerful nose to take in odors.

"Forty-four times stronger than our nose," Garcia noted.

The dog associates the explosives smell with playing a game. After a couple days, five metal training boxes are put in a line. When the dog finds the black powder, its breathing will get a little quicker, it might wag its tail, do a head spin or pull the handler. The handler tells the dog to sit and a different person throws the training towel.

In more advanced training, other strong smells such as that of fabric softener sheets and grease will be mixed in to make sure the dog can still pick out the aroma of explosives.

Luckily, Sampson hasn’t had to sit for explosives at the NJ Transit stations. If he did, a bomb squad would be called, the area would be cordoned off and evacuated and train traffic would be stopped.

With an average of 26,449 weekday rail boardings, Newark Penn Station is the most bustling train station in New Jersey.

As passengers hustled by him last week, Sampson’s nostrils got a workout as he took in such aromas as coffee and bagels. Occasionally, he sniffed a passing bag. A cacophony of sounds — announcements about a train to Harrisburg, a clacking train departure board, the hum of conversation — overloaded the senses.

Garcia takes the dog up the stairs and onto the platforms, calling out "check, check" as Sampson dutifully pokes his snout in garbage cans.

"You check everything," Garcia told a visitor. "It (an explosive device) is not going to be real exotic — it’s going to be quick. It’s not going to be under a manhole cover."

At night, Sampson stays with Garcia in the Nutley home she shares with her partner, Patty, their 9-year-old-son, Oliver, and another yellow lab.

An energetic cop who awakens at 3 a.m. so she can begin her day with an early workout at the gym, Garcia has wanted to do police work since she was a child.

But the Bayonne native went to college to study her other calling — art — and also served two years in the U.S. Army.

Garcia still draws and paints figures, but as a hobby. Sometimes, she takes composites of scenes from her workday and brings them to the canvas. In her police work, her artist’s attention to detail also has proved helpful for studying the nuances in faces.

Garcia rose from patrol officer to supervisor to sergeant before leading the K-9 unit.

"You can’t be any luckier than this," she said. "I get a dog I can bring to work every day."